Two-cycle internal-combustion engine



Feb. 4, 1930. w. L. GALVIN' TWO-CYCLE INTERNAL COMBUSTION ENGINE I Filed May 17, 1928 3 Sheets-Sheet 1 3m 05 5a an on.

m 00 WY 3 Feb. 4, 1930. w. L. GALVIN TWO-CYCLE INTERNAL COMBUSTION ENGINE Filed May '17, 1928 5 Sheets-Sheet 2 w. L. GALVIN TWO-CYCLE INTERNAL COMBUSTION ENGINE Feb. 4, 1930.

s Shets-Sheet 3 Filed May 17, 1928 Iwentop W W M e 5 during the power or Patented Feb. 4, 1930 v WILLIAM L.'G.ALVI1\T,OF CHICAGO, ILLINbIS-F wes mwo-oYoLn nrnmvAn-coivrnus'rion Emma Ap pllication filed May 17, 1928rlSeria1'No. 2 78,384.

This invention relates to improvements in positions of the main andiauxiliary pistons I throughout ,one' cycle of operation as detertwo-cycle internal combustion engines, and hasfor its principal object to providea simple. and effective means for scavenging the 5 cylinder of burned gases and for producing 1 increased suction during'each power stroke. My invention consists broadly in providing in combinationwithf a reciprocating piston and. cooperating crank shaft .of the ordinary 10 type, an auxiliary piston, movable in timed relation with respect to said. main piston so as to be substantially stationary during the early portion of the downward power stroke but to move rapidly toward said piston near 1 the end of its power stroke and approach the same so as to effectively'expel most of the exhaust gases from the cylinder, said aux 'il'iary piston also having other actuating mechanism forraising the same in advance of Q 121) the upward movement of the latter-piston so as to cooperate therewith in proper suction and compression of'thepnewrcharge in the cylinder. I

-. As a preferredoperating means" for said auxiliary piston, I utilize two separate sets of cam actuating lever systems,one for moving the piston downward during the power 5 stroke, and the other for raising the piston during the suction and compression stroke, 3 as will hereinafter more fully appear.

The invention may best be unde'rstoodby reference to the accompanying drawings, in which a v Figure lis' a diagrammatic side view of 3 a motor showing a relative arrangement of i the cylinder, main and auxiliary pistons and the lever systems for actuating 'said auxiliary piston Figure 2-is a side view of the motorshown 9 inFigure 1, showingthe general arrangement of the two sets of'lever systemsand their connection with the single auxi'liarypiston. I

Figures 3, a and 5v are diagrammatic views showing the operation of the exhaust levers main piston. p 1 Figures 6, 7 and '8 are views similar to Figures 8, 4L and 5 but showing the operation of the inlet levers duringlthe suction and compression stroke, 7

per end of the cylinder. The cylinder lO is downward stroke of the v Figure :9 is adiagram showingthe relative mined by onerevolution of thecrank shaftQ Referr ng to details of the drawings, my 55 motorincludes a' cylinder 10 having a main 'pistonoll' reciprocably movable therein and valve 16 of any well "knownform, as shown. @5

Suitable ignition means including a spark plug (not shown) or its equivalent, is provided at'a suitable point 17; adjacent the upmounted on-a crankcase 1 8. 7

,.Referring now more particularlyto the a novel features of my invention, '1 provide an auxiliary piston 20 herein of the same diameter as the main piston, and fitting within the upper end of cylinder 10-soas to form a movable head thereof. e

e The auxiliary piston is moved through two sets of lever systems which are alternately actuated by twocams and 26, rotatable in timed relation with the crank shaft 14. In the preferred form shown, these two cams are both mounted on a singlecam shaft 27 suitably driven from "the crank shaft 14 as through an idler gear28, the arran ement being such thatsaid cam shaft revo vesflyat the same speed as the crank shaft 141'. '7 r One of the sets of leversjactuated by-the cam 25 isoperativeimmediately following. the power stroke for exhausting the burned gases. These levers and their actuatingcam will hereinafterbe referred .to as the 1y. As shown herein, the exhaust levers -inelude a bell crank lever 30having one end thereof provided with aroller 31 adaptedfor second bell crank lever 33;: The two bell crank levers are respectively fixed upon pivot ex. .haust levers, and exhaust cam, respective [engagement with the exhaust cam 25 andithe other end connected through a link 32 :to an:

' and cam.

link 48 to a push rod 49.

I end to a link connected to a push rod 37.

Said push rod extends through a suitable bearing 38 supported in the upper end of the crank case 18. u

The upper end of the push rod 37 is connected through a link 39 tonne arm 40 of a i yoked rocking lever 40 which is arched upwardly over the cylinder 10 and is pivoted on a bracket 10. Said rocklnglever isconnected at its upper end to the auxiliary piston 20' through the pivoted link 41. The arrangement of the exhaust levers and actuating cam is such as to provide a'very rapid downward movement of the auxiliary piston at a speed approximating four-to-one over the speed of the main piston during a certain period of downward movement of the latter, as will hereinafter more fully appear.

Referring now to the system of levers and their actuating cam 26, hereinafter referred to as the intake levers and intake cam, respectively, the same consists-of a system somewhat similar to that of the exhaust levers but arranged for moving the auxiliary piston upwardly and at a somewhat lower rate of speed than that caused by the exhaust levers The intake levers include a bell crank lever 4:2 having'one end thereof pro vided with a roller 43 for engagement with the intake cam 26 and having its otherend connected through a link 44 to a bell crank lever 45. The two bell crank levers 42 and 45. are pivotally mounted respectively on fixed pins 4 and 45 The inner end of the bell crank lever 45 is connected bylink 46'to an intermediate point of lever 47 which lever constitutes a lever of the third class, being pivotally mounted at one end on a fixed pivot pin 47 and at the other end connected through Said push rod ex; tends upwardly through suitable bearing 49 in the top of crank case 18 and is connected to another arm 40 of rocking member 40 by means of a link 49*.

The operation of the engine above described is best shown in Figures 3 to 8, taken in connection with the motion diagram in Figure 9. r In the latter diagram, the upper heavy line 20 represents the movement of the auxiliary piston20, the lower line'll represents the relativeimovement of the main piston, and the corresponding angular movement of the crank shaft is indicated at the seV-J eral points of one revolution by the several vertical lmesmarked 0, 45, 90?, etc., from the initial point of each cycle;

Referring now to the description of one cycle of. operation, Figure 3 indicates the relative position of the parts when the main piston has just passed dead center, wi h the crank shaft rotating in a clockwise direction,

and in which the charge within the cylinder has been ignited so as to start the piston downward on its power stroke. As will be seen from Figure 3, the'exhaust cam 25 is rotating in a clockwise direction but has not yetreached a position to move the exhaust levers and through the latter to move the auxiliary piston. Accordingly, the auxiliary piston is 'beseenithat this downward movement of the auxiliary piston is "extremely rapid, (being about fourtimes as fast as-the main piston) so that a full stroke of the auxiliary piston is completed Within a range of approximately 25, that is to say, between about 90 and 115 of rotation of the crank shaft and before the main piston begins to open the inlet valve; At the bottom of the auxiliary'pistons stroke its lower surface almost meets the upper surface of the main piston at a point opposite the exhaust port, so as to force practically all of the burned gases from the cylinder through the exhaust port, as will be understood from the diagram, and as also shown in Figure 5.

At this point the exhaust stage is completed, and the exhaust cam rotates out of engagement with its lever system.

Immediately thereafter, the inlet cam 26 comes into operative engagement with the inlet levers, as indicated in Figure 6. The inlet levers are then actuated to raisethe auxiliary piston while the main piston continues its downward movement, but the arrangement of the inlet levers is such as to cause somewhat slower upward movement of said auxiliary piston (about 2 to 1 relative to the main piston) than is its downward movement;

As a result of said upward movement ofthe auxiliary piston, it will be seen from Fig ure 9 that the two pistons are moving away from each other until the main piston reaches the lowermost limit of its stroke, and during this period the main piston has passed below the upperedge of the inlet port so as to open the same. The rapid separation of the two pistons therefore produces a suction stroke for intake of a fresh ch rge between the points represented by lines 115 and 245 the auxiliary piston completes its upward 1 30 each other so as to permit the exhaust cam movement, as shown in Figure 7, this being at about 245 of rotation of the crankshaft. -After the intake port has been closed, the

main piston continues to move upwardly to and lever to become operative during the next succeeding cycle.

Referring now more particularly to the advantages of a two-cycle engine as above described, it will be observed, first, that the full effect of combustion of thepower stroke is effective uponthe main piston but approximately all burned gases are expelled from the cylinder as soon as theje'xhaust port is open. Second: A new charge s drawn into the cylinder by cooperation of the auxiliary and main pistons to form a suctionstroke,said

charge being relatively large ands-therefore capableot producing a high compression. From a'structural standpoint also, my 1111- proved motor has the advantages of utilizing a simple form of cam and compound, speed of mechanical valves, andI findthat'the lever systems shown aremore compact and posi-' tive in operation than is possible with cam devices which might be devisedto give equal relative movements of the auxiliarypiston.

WhileI have illustrated and described the particular embodiment of my invention, it will be understood that I do not wish to be limited to the exact construction shown and described but that various changes and modiflcations may be made without departing from the spirit and scope of'my, invention. 1

5 I claim as my invention 1. In a two-cycle internal combustion engine,'a cylinder, a power piston and an auxiliary piston both reciprocably movable in v said cylinder, an inlet port adjacent the lower 7 limit of movement of said power piston,lan exhaust port above'said inlet port, and means in timed relation with said power piston'for movingsaid auxiliary piston downwardly after the explosion so as to approach the power piston and expel vthe burned gases through said exhaust port during an intermediate portion of the downwardstroke of" said power piston, and means for moving said auxiliary piston-upwardly during the final portion of thedownward strokeof said power piston whereby both of said pistons cooperate,

in producin suction for intake [Of gases through said intake port, said'meanstor moving said auxiliary piston downwardlyand upwardly in timed relation with saidinain pis- .gine,a'cylinder, a power piston and an auxjiliary piston both reciprocably movable in ton comprising two' independently actuated successively operable compoundvleverfsys tei'ns. Y A r o.

2.111 atwo-cycle internal combustion ensaid cylinder, an inlet port adjacent the lower limit of movement of said power" piston, an exhaust port above said inlet port, a compound lever system actuated in timed rela a second compound lever system" for moving said auxiliary piston upwardly during'the final portion of the downward stroke of said power piston whereby both of said pistons cooperate in producing suction for intake of gases through said intake port, said lever systems having independent cam actuating means therefor.

i 3. Inatwo cycle internal combustion engine, a cylinder, a power. piston andjan EMXll-f iary-piston botlireciprocably movable in said exhaust port above said inletportfa com- -tion" wi.th said power piston for movinglsaid auxiliarypiston downwardly after the explo- I'sion so as to: approach the power piston and expel the burned gases through said exhaust port during an intermediate portion'o f the downwardstr-oke of said power piston, and;

cylinderpan inlet portpadjacent the lower 1 'l mit. of movement of said powerpiston, an- I F increasing levers for operating the auxiliary P l ys ct 1 m re1apiston instead of a more complicated system a second compound lever systein'for moving J said auxiliary piston upwardly during the final portion of the downward stroke of said power piston whereby both of said pistons cooperate in producing suction for intake of gases through said intake port, said lever systems having independent cam actuating means therefor, and the first leversystem moving said auxiliary piston downwardly at approximately'four times the speed of said power piston.

i 4. Ina two-cycle internal combustion en-- gine, a cylinder, a power piston and an auxiliary piston both reciprocably' movable in said cylinder, an inlet port adjacent thelower limit of movement of said" power piston, an exhaust port above said inlet port, a

compound lever system actuated in timed relation with: said power piston for moving said auxiliary piston downwardly after the ex- I .plosion so as to approach the power'piston and expel. the burned gases through said ex- 1 liaust port duringan intermediate portion of the downward stroke of said power piston, and a second compound lever system for moving said auxiliary piston upwardly during the final p-ortion'of the downward stroke of said power piston whereby both of said pistons cooperate in producing suction for intake of gases through said intake port, said lever systems having independent cam actuating means therefor, and said first lever system moving said auxiliary piston downward ly at approximately twice the speed of upward movement produced by said second lever system.

5. In a two-cycle internal combustion en-l gine, a cylinder, a power piston and an auxiliary piston both reciprocably movable in said cylinder, an inlet port adjacent the lower limit of movement of said power piston, an exhaust port above said inlet port, a compound lever system actuated in timed relation with said power piston for moving said auxiliary piston downwardly after the explosion so as to approach the power piston and expel the burned gases through said exhaust port during an intermediate portion of the downward stroke of said power piston, and a second compound lever system for moving said auxiliary piston upwardly during the final portion of the downward stroke of said' power piston whereby both of said pistons cooperate in producing suction for intake of gases through said intake port, said lever systerns having independent cam actuating means therefor, and the first lever system moving said auxiliary piston downwardly at approximately fourtimes the speed of said power piston, and said second lever system moving said auxiliary piston upwardly at approximately one half the speed of down ward movement produced by said first lever system. 7 i

Signed at Chicago, 111., this 12th day of May, 1928. Y

- WILLIAM L. GALVIN. 

